Understanding What Are Two Drugs Contraindicated in Glaucoma?: Corticosteroids and Anticholinergics

Studies have shown that over 90% of patients with pre-existing primary open-angle glaucoma experience an increase in intraocular pressure when exposed to topical corticosteroids. It is critical to know what are two drugs contraindicated in glaucoma, specifically corticosteroids and anticholinergics, to prevent serious vision loss by avoiding potential complications.

Quick Summary

Corticosteroids and anticholinergics can significantly raise intraocular pressure and must be used with caution or avoided by glaucoma patients. Their effects vary depending on the type of glaucoma and administration route, emphasizing careful medication management.

Key Points

• Corticosteroids can elevate intraocular pressure (IOP): Prolonged use of steroids in any form, including oral, inhaled, and topical, can increase IOP and worsen open-angle glaucoma.

• Anticholinergics cause pupil dilation: In people with narrow angles, this can precipitate an acute and painful angle-closure glaucoma attack.

• Different drug classes affect different glaucoma types: Corticosteroids primarily affect open-angle glaucoma, while anticholinergics are a major risk for angle-closure glaucoma.

• Comprehensive communication is vital: Patients must inform all their healthcare providers about their glaucoma diagnosis to avoid contraindicated medications.

• Acute angle-closure is a medical emergency: Symptoms like severe eye pain, headache, and blurred vision require immediate medical attention to prevent permanent vision loss.

• Avoidance is key for safety: For patients with glaucoma, the best approach is to avoid these contraindicated drug classes whenever a safe, non-contraindicated alternative is available.

The Primary Culprits: What Are Two Drugs Contraindicated in Glaucoma?

For individuals with glaucoma, certain medications can exacerbate the condition or trigger acute, dangerous episodes. Among the most critical drug classes to avoid or use with extreme caution are corticosteroids and anticholinergics. Both can interfere with the eye's delicate fluid balance, leading to elevated intraocular pressure (IOP) and potential optic nerve damage.

Corticosteroids and Open-Angle Glaucoma

Corticosteroids, commonly known as steroids, are potent anti-inflammatory drugs used to treat a wide array of conditions, from asthma and allergies to autoimmune diseases. However, their use is strongly linked to an increase in IOP, especially in patients with open-angle glaucoma.

Mechanism of Action

The primary mechanism behind steroid-induced glaucoma involves increased resistance to the outflow of aqueous humor, the fluid inside the eye. Corticosteroids are believed to cause morphological changes in the trabecular meshwork, the eye's drainage system, which inhibits proper fluid drainage. This buildup of fluid directly increases IOP.

Administration Routes and Risks

Crucially, the risk of IOP elevation is not limited to topical steroid eye drops. Steroids can affect eye pressure regardless of the administration route, including:

• Oral steroids: Medications like prednisone taken by mouth for inflammatory conditions.
• Inhaled steroids: Used for asthma and COPD (e.g., fluticasone nasal spray).
• Topical steroids: Creams and ointments applied to the skin, particularly on the face, as well as ophthalmic eye drops.
• Injected steroids: Joint injections or intravitreal (inside the eye) injections.

Anticholinergics and Angle-Closure Glaucoma

Anticholinergic drugs block the action of acetylcholine, a neurotransmitter involved in various bodily functions, including pupil size regulation. While helpful for treating conditions like overactive bladder or asthma, they can trigger a medical emergency in people with narrow-angle glaucoma.

Mechanism of Action

The danger lies in their mydriatic effect, meaning they cause the pupil to dilate. In eyes with a narrow drainage angle, pupillary dilation can cause the iris to bunch up and physically block the trabecular meshwork, halting aqueous humor drainage completely. This rapid and severe increase in IOP is known as an acute angle-closure glaucoma attack and can lead to permanent vision loss in a matter of hours.

Common Sources of Anticholinergics

Many people are unaware they are taking anticholinergic medications because they are present in common prescription drugs and over-the-counter (OTC) remedies. These include:

• Certain antidepressants (e.g., tricyclics like amitriptyline).
• Asthma and COPD medications (e.g., ipratropium).
• Medications for overactive bladder or incontinence (e.g., oxybutynin).
• Certain antihistamines (e.g., diphenhydramine) and decongestants.
• Some anti-nausea and motion sickness drugs.

Distinguishing the Glaucoma Types and Risks

The risk profile of these contraindicated drugs depends heavily on the type of glaucoma a patient has. Understanding the difference is vital for patient safety.

Feature	Open-Angle Glaucoma	Angle-Closure Glaucoma
Prevalence	Most common form.	Less common, but more acute.
Mechanism	The drainage angle is open, but fluid outflow is slow over time.	The drainage angle is anatomically narrow and can become suddenly blocked.
Symptoms	Often asymptomatic in early stages.	Can cause severe eye pain, blurred vision, headache, nausea, and halos around lights during an attack.
Steroid Risk	High risk of increased IOP, can worsen the condition.	Can also increase IOP, but generally less of a concern than in open-angle.
Anticholinergic Risk	Lower risk of causing an acute event, but still should be used with caution.	High risk of triggering an acute, dangerous attack.

Important Considerations for Patients

Managing glaucoma requires careful attention to all medications being taken, not just eye drops prescribed specifically for the condition. Communication and proactive monitoring are key.

Steps for Proactive Patient Management

1. Inform all providers: Always tell every healthcare professional—including your primary care physician, specialists, and pharmacists—that you have glaucoma.
2. Maintain an updated list: Keep a comprehensive and current list of all medications, including OTC drugs, supplements, and herbal remedies.
3. Schedule regular check-ups: Stick to a regular schedule of eye exams with your ophthalmologist to monitor your IOP and optic nerve health.
4. Discuss alternatives: If a medication that could worsen glaucoma is prescribed, ask your doctor about alternative treatment options.
5. Watch for warning signs: In case of an acute angle-closure attack, seek immediate medical attention if you experience severe eye pain, headache, or visual disturbances like seeing halos around lights.

Other Potentially Harmful Medications

While corticosteroids and anticholinergics are two major concerns, other drug classes should also be used with caution, including:

• Certain sulfonamide-containing drugs (e.g., topiramate, some diuretics).
• Some antidepressants, like SSRIs and SNRIs, and certain antipsychotics.
• Sympathomimetics (e.g., decongestants like pseudoephedrine).
• Oral beta-blockers, which can have complex effects or interact with glaucoma eye drops.

Conclusion

Understanding what are two drugs contraindicated in glaucoma is a critical part of a patient's care plan. The risks associated with corticosteroids and anticholinergics—which can raise intraocular pressure in open-angle glaucoma or trigger an acute attack in narrow-angle glaucoma—cannot be overstated. Effective glaucoma management is a collaborative process between the patient and their healthcare team. By maintaining open communication and remaining vigilant about all medications, individuals with glaucoma can better protect their vision and overall eye health. For additional resources and information, consider visiting the Glaucoma Research Foundation.

Frequently Asked Questions

Can inhaled steroids cause glaucoma?

Yes, steroids administered via any route, including inhalers for asthma, can increase intraocular pressure and worsen glaucoma, especially with long-term use. All healthcare providers should be aware of a patient's glaucoma status.

What happens during an acute angle-closure glaucoma attack?

During an acute attack, the pupil dilates, causing the iris to block the drainage pathway in eyes with narrow angles. This leads to a sudden, severe increase in intraocular pressure, which can rapidly damage the optic nerve and cause vision loss.

Are over-the-counter cold medicines safe for people with glaucoma?

No, many over-the-counter cold and flu remedies contain anticholinergics or decongestants that can dilate the pupil and increase the risk of an angle-closure attack in susceptible individuals. Always check with your eye doctor before using these products.

How can I tell if my risk for drug-induced glaucoma is high?

Your risk is higher if you have pre-existing open-angle glaucoma, narrow drainage angles, a family history of glaucoma, or if you take higher doses or long courses of contraindicated medications. Your ophthalmologist can perform tests to assess your risk.

If I must take a steroid, what precautions should I take?

If a steroid is necessary, work closely with your ophthalmologist and the prescribing physician. They may choose a less potent steroid, prescribe the lowest effective dose, or recommend increased monitoring of your intraocular pressure to mitigate the risk.

What are some common medications with anticholinergic effects?

Common medications with anticholinergic effects include certain antidepressants (e.g., amitriptyline), anti-nausea and motion sickness drugs (e.g., scopolamine), and some medications for bladder control (e.g., oxybutynin).

Can discontinuing corticosteroids reverse the effects on eye pressure?

In many cases, the elevated intraocular pressure caused by corticosteroids will return to normal after the medication is discontinued. However, prolonged use or high sensitivity can sometimes lead to irreversible damage. Regular monitoring is essential.